This invention concerns wheels for example, but not exclusively, for wheelchairs and other means of conveyance, for example bicycles.
Cycle and wheelchair wheels were originally made with solid rubber tires. Subsequently the solid rubber tire was replaced by tires with pneumatically inflatable inner tubes, these having the advantage that they act as shock absorbers when travelling over uneven surfaces.
The change to pneumatic tires dramatically improved the comfort, road holding and safety of vehicles which used them, especially at the higher speeds which could be obtained with their use.
More recent developments have led to cycles of more sophisticated design which include separate shock absorbers to absorb greater shocks than can be absorbed by pneumatic tires alone, for example spring suspensions of the forks for the front and/or rear wheels.
Despite improvements in the suspension of cycles, apart from the use of pneumatic tires, wheelchairs have generally relied on no more than the use of rubber bushings for mounting the axles to provide shock absorption. Such suspension systems serve to reduce the unsprung weight of the wheelchair to more nearly that of the wheel which is supported by the tires and so improve their ride.
The introduction of battery powered assistance for cycles, wheelchairs and other types of conveyance which include motors in the wheels has resulted in an increase in wheel weight which demands increased shock absorbing performance from the tires due to the increased weight leading to increased rolling resistance for the tires and decreased lateral stability. However, the suspension systems referred to above do not in general improve the situation because the wheels themselves are unsprung.
According to the present invention there is provided a wheel for a bicycle, wheelchair or the like comprising an inner rim attached to a wheel hub, an outer rim for receiving a tires, and a resilient member between the inner and outer rims which in use serves to absorb shocks from the surface over which the wheel passes.
The invention also provides bicycles and wheelchairs including at least one wheel in accordance with the present invention.